1. Field of the Invention
The present invention relates to a golf ball of a multilayer structure having a rubber thread layer wrapped around the center, exhibiting favorable spinning performance and shot feeling as well as a long flight distance.
2. Description of the Background Art
A golf ball of a multilayer structure having a rubber thread layer is configured by wrapping a cover around a rubber thread layer formed by having rubber thread wound around a solid center or a liquid center in an elongated state. Such a golf ball of a multilayer structure having a rubber thread layer is superior to a two-piece golf ball with a cover wrapped around a solid core in the shot feeling and controllability. However, the spin rate is high and the flight distance cannot be easily increased due to the small launch angle. Amateur golf players generally have a tendency for the two-piece golf ball that exhibits longer flight distance than the golf ball of a multilayer structure having a rubber thread layer.
Several approaches have been made to increase the flight distance of a conventional thread-wound golf ball with a solid center. For example, U.S. Pat. No. 5,848,942 discloses the definition of the center diameter to 30-38 mm, and the center hardness distribution, the cover flexural modulus and the like to a predetermined range. U.S. Pat. No.5, 853,337 discloses the approach of using a cover of high hardness as well as the definition of the center diameter to 30-38 mm and defining the difference between the load deformation of the center and the load deformation of the ball. Japanese Patent Laying-Open No. 10-201881 discloses the definition of the load deformation of the center, the cover hardness, and the flexural modulus to a predetermined range with the center diameter set to 30-38 mm. However, the disclosed art cannot improve the flight distance while maintaining the superior spin performance of a thread-wound golf ball.
An object of the present invention is to provide a thread-wound golf all exhibiting favorable spin performance and shot feeling with a long light distance equal to or longer than the flight distance by a two-piece solid golf ball by increasing the adherence between a rubber thread layer and cover in a golf ball of a multilayer structure having a rubber thread layer.
The thread-wound golf ball of the present invention has a cover wrapped around a rubber thread layer formed by winding rubber thread around the center. The ratio of the volume of the rubber thread layer to the volume of the entire thread-wound golf ball is 10-20%. When the deformation (mm) from the state of applying a load of 98N to a load of 1274N to the center is A, and the deformation (mm) from the state of applying a load of 98N to a load of 1274N to a thread-wound core having rubber thread-wound around the center is B, the difference in deformation (Axe2x88x92B) is 0.5-0.7. The shore D hardness of the cover is 50-60.
It is preferable that the thickness of the cover is 1.0-2.0 mm, and the deformation (mm) A from the state of applying a load of 98N to a load of 1274N to the center is 3.5-4.1. Also, it is preferable that the deformation (mm) B from the state of applying a load of 98N to a load of 1274A to the thread-wound core having rubber thread-wound around the center is 2.7-3.4.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawing.